/****************************************************************************
**
** Copyright zjzdy
**
** This source code is licensed under under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
****************************************************************************/

// Most of the code here was originally written by Qt term,
// and the grateful thanks of the Qt team.

#include "isciicodec_p.h"
#include "textcodec_p.h"
namespace zdytool {
	struct Codecs {
		const char name[10];
		ushort base;
	};

	static const Codecs codecs [] = {
		{ "iscii-dev", 0x900 },
		{ "iscii-bng", 0x980 },
		{ "iscii-pnj", 0xa00 },
		{ "iscii-gjr", 0xa80 },
		{ "iscii-ori", 0xb00 },
		{ "iscii-tml", 0xb80 },
		{ "iscii-tlg", 0xc00 },
		{ "iscii-knd", 0xc80 },
		{ "iscii-mlm", 0xd00 }
	};

	TextCodec *IsciiCodec::create(const char *name)
	{
		for (int i = 0; i < 9; ++i) {
			if (TextCodecNameMatch(name, codecs[i].name))
				return new IsciiCodec(i);
		}
		return 0;
	}

	IsciiCodec::~IsciiCodec()
	{
	}

	string IsciiCodec::name() const
	{
	  return codecs[idx].name;
	}

	int IsciiCodec::mibEnum() const
	{
		/* There is no MIBEnum for Iscii */
		return -3000-idx;
	}

	static const uchar inv = 0xFF;

	/* iscii range from 0xa0 - 0xff */
	static const uchar iscii_to_uni_table[0x60] = {
		0x00, 0x01, 0x02, 0x03,
		0x05, 0x06, 0x07, 0x08,
		0x09, 0x0a, 0x0b, 0x0e,
		0x0f, 0x20, 0x0d, 0x12,

		0x13, 0x14, 0x11, 0x15,
		0x16, 0x17, 0x18, 0x19,
		0x1a, 0x1b, 0x1c, 0x1d,
		0x1e, 0x1f, 0x20, 0x21,

		0x22, 0x23, 0x24, 0x25,
		0x26, 0x27, 0x28, 0x29,
		0x2a, 0x2b, 0x2c, 0x2d,
		0x2e, 0x2f, 0x5f, 0x30,

		0x31, 0x32, 0x33, 0x34,
		0x35, 0x36, 0x37, 0x38,
		0x39,  inv, 0x3e, 0x3f,
		0x40, 0x41, 0x42, 0x43,

		0x46, 0x47, 0x48, 0x45,
		0x4a, 0x4b, 0x4c, 0x49,
		0x4d, 0x3c, 0x64, 0x00,
		0x00, 0x00, 0x00, 0x00,

		0x00, 0x66, 0x67, 0x68,
		0x69, 0x6a, 0x6b, 0x6c,
		0x6d, 0x6e, 0x6f, 0x00,
		0x00, 0x00, 0x00, 0x00
	};

	static const uchar uni_to_iscii_table[0x80] = {
		0x00, 0xa1, 0xa2, 0xa3,
		0x00, 0xa4, 0xa5, 0xa6,
		0xa7, 0xa8, 0xa9, 0xaa,
		0x00, 0xae, 0xab, 0xac,

		0xad, 0xb2, 0xaf, 0xb0,
		0xb1, 0xb3, 0xb4, 0xb5,
		0xb6, 0xb7, 0xb8, 0xb9,
		0xba, 0xbb, 0xbc, 0xbd,

		0xbe, 0xbf, 0xc0, 0xc1,
		0xc2, 0xc3, 0xc4, 0xc5,
		0xc6, 0xc7, 0xc8, 0xc9,
		0xca, 0xcb, 0xcc, 0xcd,

		0xcf, 0xd0, 0xd1, 0xd2,
		0xd3, 0xd4, 0xd5, 0xd6,
		0xd7, 0xd8, 0x00, 0x00,
		0xe9, 0x00, 0xda, 0xdb,

		0xdc, 0xdd, 0xde, 0xdf,
		0x00, 0xe3, 0xe0, 0xe1,
		0xe2, 0xe7, 0xe4, 0xe5,
		0xe6, 0xe8, 0x00, 0x00,

		0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00,
		0x01, 0x02, 0x03, 0x04, // decomposable into the uc codes listed here + nukta
		0x05, 0x06, 0x07, 0xce,

		0x00, 0x00, 0x00, 0x00,
		0xea, 0x08, 0xf1, 0xf2,
		0xf3, 0xf4, 0xf5, 0xf6,
		0xf7, 0xf8, 0xf9, 0xfa,

		0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00
	};

	static const uchar uni_to_iscii_pairs[] = {
		0x00, 0x00,
		0x15, 0x3c, // 0x958
		0x16, 0x3c, // 0x959
		0x17, 0x3c, // 0x95a
		0x1c, 0x3c, // 0x95b
		0x21, 0x3c, // 0x95c
		0x22, 0x3c, // 0x95d
		0x2b, 0x3c, // 0x95e
		0x64, 0x64  // 0x965
	};


	string IsciiCodec::convertFromUnicode(const ushort *uc, int len, ConverterState *state) const
	{
		char replacement = '?';
		bool halant = false;
		if (state) {
			if (state->flags & ConvertInvalidToNull)
				replacement = 0;
			halant = state->state_data[0];
		}
		int invalid = 0;

		std::vector<char> result(2 * len + 1);
		result[2 * len] = '\0';


		uchar *ch = reinterpret_cast<uchar *>(result.data());

		const int base = codecs[idx].base;

		for (int i =0; i < len; ++i) {
			const ushort codePoint = uc[i];

			/* The low 7 bits of ISCII is plain ASCII. However, we go all the
			 * way up to 0xA0 such that we can roundtrip with convertToUnicode()'s
			 * behavior. */
			if(codePoint < 0xA0) {
				*ch++ = static_cast<uchar>(codePoint);
				continue;
			}

			const int pos = codePoint - base;
			if (pos > 0 && pos < 0x80) {
				uchar iscii = uni_to_iscii_table[pos];
				if (iscii > 0x80) {
					*ch++ = iscii;
				} else if (iscii) {
					const uchar *pair = uni_to_iscii_pairs + 2*iscii;
					*ch++ = *pair++;
					*ch++ = *pair++;
				} else {
					*ch++ = replacement;
					++invalid;
				}
			} else {
				if (uc[i] == 0x200c) { // ZWNJ
					if (halant)
						// Consonant Halant ZWNJ -> Consonant Halant Halant
						*ch++ = 0xe8;
				} else if (uc[i] == 0x200d) { // ZWJ
					if (halant)
						// Consonant Halant ZWJ -> Consonant Halant Nukta
						*ch++ = 0xe9;
				} else {
					*ch++ = replacement;
					++invalid;
				}
			}
			halant = (pos == 0x4d);
		}
		string result_str(result.data(),ch - (uchar *)result.data());

		if (state) {
			state->invalidChars += invalid;
			state->state_data[0] = halant;
		}
		return result_str;
	}

	u16string IsciiCodec::convertToUnicode(const char* chars, int len, ConverterState *state) const
	{
		bool halant = false;
		if (state) {
			halant = state->state_data[0];
		}

		std::vector<uint16_t> result(len+1);
		result[len] = '\0';
		ushort *uc = result.data();

		const int base = codecs[idx].base;

		for (int i = 0; i < len; ++i) {
			ushort ch = (uchar) chars[i];
			if (ch < 0xa0)
				*uc++ = ch;
			else {
				ushort c = iscii_to_uni_table[ch - 0xa0];
				if (halant && (c == inv || c == 0xe9)) {
					// Consonant Halant inv -> Consonant Halant ZWJ
					// Consonant Halant Nukta -> Consonant Halant ZWJ
					*uc++ = ushort(0x200d);
				} else if (halant && c == 0xe8) {
					// Consonant Halant Halant -> Consonant Halant ZWNJ
					*uc++ = ushort(0x200c);
				} else {
					*uc++ = ushort(c+base);
				}
			}
			halant = ((uchar)chars[i] == 0xe8);
		}
		u16string result_str(result.data(),uc - result.data());

		if (state) {
			state->state_data[0] = halant;
		}
		return result_str;
	}
}